The present invention relates to conveyor idlers and especially to an apparatus for molding an elongated, flexible, solid polymer idler having metal shafts formed in each end, along with the process for molding the idler and the idler apparatus molded by the process.
In the past, it has been common to provide troughing idlers for conveyor belts and these include flexible troughing idlers of the suspension type. Flexible idlers of the suspension type have achieved commercial success as substitutes for previous conventional types of troughing idler having rigid rollers mounted on fixed axes in certain demanding applications. One such flexible troughing idler of the suspension type includes that illustrated in U.S. Pat. No. 3,876,890 to which provides for an idler structure molded on a wire cable to the ends of which are short shafts swaged to the cable in which the wire cable is held to each end by two terminal bearings and in which the molded rollers are molded from neoprene or the like. Variations of the type of material to be conveyed frequently calls for various trough depths and curvatures. In installations using previous conventional composite troughing idlers formed of individual rotatable rollers, adjustment of the outer ends of the outer rolls was seldom provided for and any desired degree of troughing was determined by the angularity of the axis of the concentrator roller. Since the rollers have rigid inflexible axes, adjustment of the ends to vary troughing curvatures is a necessity on a radius determined by the roller length. With the advent of the flexible, suspension type troughing idlers, adjustment of the suspension point became more feasible. In my prior U.S. Pat. No. 3,033,352 for a Conveyor Idler Mounting Means and Support, I provided an adjustable support for the outer extremities of idler support rollers for conveyor belts of a flexible suspension type troughing idlers which provided for a lateral adjustment to be affected as an incident to the vertical adjustment. These prior art flexible troughing idlers and mounts have worked satisfactorily for many years, but the rise in the cost of raw materials has substantially increased the price of the terminal bearings and thereby substantially increased the cost of suspension troughing idlers and their supporting systems. It is accordingly one advantage of the present invention to provide a molded conveyor idler which is easily formed of polymer materials for providing the necessary strength to support conveyor belts for long periods without failure at less costs.
In my prior U.S. Pat. No. 4,011,938 for a Suspension Idler, I provide for a conveyor idler and idler terminal bearing which has a one-piece, molded, elongated, flexible, polymer idler having a plurality of rollers formed thereon. Each end of the idler has an enlarged portion which is engaged by terminal supports surrounding the enlarged portion to rotatably hold the idler in its mount. The terminal supports are made entirely of polymer materials, but may have a steel pin mounted thereto for mounting to the conveyor idler mount. The present invention is an improvement over this prior U.S. Patent and provides a terminal connection of increased strength in a polymer idler, without using a cable, or a chain, or the like, molded therein. Through a process that assures the exact same length of each idler and avoids alignment problems and entrapped air during molding in a process for making a conveyor idler.
Other typical, flexible idler rollers having a cable or chain center can be seen in U.S. Pat. No. 3,182,788 to Donadio, et al., and in U.S. Pat. No. 3,182,787 to Lorenz, and other patents of interest may be seen in the U.S. and foreign patents cited as references in my prior U.S. Letters Pat. No. 4,011,938. Molding of prior art suspension idlers is accomplished in a horizontal mold and requires tension on the cable in an attempt to achieve concentricity of the cable and molded idler. However, exact concentricity is not obtained and the idlers have small variations in length. For example, in the case of a suspension idler used in conjunction with a 30 inch conveyor belt, laterial movement of one support bearing 1/8 inch would effect a change in belt line height by 3/8 inch. Further, if this dimension were raised, it would result in overloading of that particular belt support and conversely, if it were lowered, it would result in poor contact and failure due to vibrations. It is accordingly an aim of the present invention to provide an elongated, flexible, suspension idler made of solid polymer material, such as a high density polyurethane having end shaft members molded thereinto and a molding apparatus and molding process that avoid the prior problems experienced in molding and using solid polymer suspension idlers.